Woven resistor



R. E. TARPLEY WOVEN RESISTOR Filed Qct.

4 Sheets-Sheet 1 INVENTOR.

ZL La LMA wwow ATTORNEY May 7, 1940.

' Filed Oct. 25, 1936 R. E. TARPLEY WOVEN RESISTOR 4 Sheets-Sheet 2 INVENTOR.

I WQWM ATTORNEY.

y 7, 1940- R. E. TA-RPLEY 2.199.810

WOVEN RESISTOR Filed Oct. 23, 1936 4 Sheet-Sheet 5 wow/w 4, a mm x BY M a) w 118 comm w -J- A TTORNEYv R. E. TARPLEY WOVEN RESISTOR May 7, 1940.

Filed Oct. 23. 1936 4 Sheets-Sheet INVENTOR. BY W A TTORNEY.

Patented May 7, 1940 UNITE-D. STATES WOVEN nas'rs'ron Raymond E. 'Iarplcy, Philadelphia, Pa... allignor needs & Northrup Company, Philadelphia Pa, a corporation of Pennsylvania Application October 23, 1936, Serial No. 107,139

20 Claims.

My invention relates to resistors or resistance units particularly suited for use in attenuators. in high fidelity amplifying systems, in circuits or networks involving high precision measurements 5 especially at high frequencies, including high radio frequencies, and in general for uses in which the phase angles of resistors must be negligible.

In accordance with my invention, the resistance conductor is woven to form a m'ulti-ply or multi- 10 layer web; in the cross-section of some modifications, the woven conductor appears as a plurality of serially-connected bifilar loops, one for each layer of the web; in the cross-section of other modifications, the woven conductor appears as'a ll single, folded bifilar loop, the number of folds depending upon a number of layers of the web; in the cross-section of another modification woven with two conductors, the conductors appear I as biiilar loops in different layers or plies; in other 50 modifications woven with two or more conductors,

.atleast one of the conductors is woven into one of the layers of webbing to form bifilar loops, and

the other conductor or conductors may be woven in the other layer or layers of the webbing in the U simple manner common in textiles.

My invention further resides in features of construction, combination, and arrangement hereinafter described and claimed.

For an understanding of my invention, refer- I ence is to be had to the accompanying drawings in which:

Flg.-1 illustrates the weaving pattern" of one modification;

Fig. 1a isa connected series of cross-sections taken on lines A-A, BB, CC, and D-D of I Fig. 1;

Figs. lb-le are explanatory figures referred to in description of Figs. 1 and la;

Fig. 2 illustrates the weaving pattern of a sec- 4. nd modification; Fig. 2a is a connected series of cross-sections taken on lines E-E, F-F, G-G and H-I-I of Fi 2;

Fig. 3 illustrates the weaving pattern of a third .modiflcation;

. Fig. 3a is a connected series of cross-sections taken on lines I-'-I, J--J, K-K and L-L of .Fi 3;

Fig. 4 is an end viewof a fourth modification 50 ofthe invention;

Fig. a is a top plan view of the top layer of Fig. 4 owing the weaving pattern thereof;

Fig. 4b is a top plan view of the lower layer of Fig. 4showing the weaving pattern thereof;

Fig. 4c is a connected series of cross-sections taken on lines M-M, N-N, 0-0, and P-P of Figs. 4a and 4b:

Fig. 5 is a connected series of a modification of Fig. 4;

Fig. 6- is similar to P18. 1 except the web has a 5 greater number of plies; I

Fig. 7 is similar to Fig. 3a except the web has a greater number of plies;

Fig. 8 illustrates an arrangement for measuring the voltage ratio of a potential transformer;

Fig. 9 is a connected 'series of cross-sections of, resistance webbing used in the system of Fig. 8;

Fig. 10 is a modification of Fig. 8;

Fig. 11 is'a connected series of cross-sections of resistance webbing used in the systems of Fig. 10

Fig. 12 is another modification of Fig. 8;

Fig. 13 is a connected series of cross-sections of resistance webbing used in the'system of Fig. 12.

The resistors used in measuring circuits or ap-= paratus such as voltage dividers, bridges, attenuators, or the like, are usually calibrated with direct current or current of a particular frequency; for current measurements at other, and oftenwidely different frequencies, it is essential that the resistors have negligible inductance and capacity, 2 otherwise the variation in phase angle of the resistorsintroduces error whose magnitude is dif-- ierent for diiferent frequencies and for different settingsof the apparatus.

In resistance-coupled amplifiers, it ishighly desirable the coupling resistors have negligible inductance and capacity, otherwise the amplifier is subject to frequency discrimination which in audio-frequency amplifiers affects the quality of the reproduced sound.

As will hereinafter appear, resistors constructed in accordance with my invention exhibit substantially pure andconstant resistance even at high radio frequencies, for example, of the order of of cross-sections four megacycles per second and higher. 0

Referring to .Figs. 1 and la, the resistance conductor RC is woven of: two warps of suitable material as silk threads; the upper warp comprises the warp threads or elements Wl, W2, W3, etc; and the lower warp comprises the warp threads or elements wl, 102, wt, etc.

The actual number of warp elements is, of course, substantially greater .than shown in Figs.

1 and 1a illustrative of the weaving pattern; for clarity, the size of the warp threads and of the conductor is exaggerated; for like reason, the spacing between the elements of the warp and between the picks of conductor is also exaggerated. upper warp comprises the threads WI W2,

W3, etc. and the lower warp comprises the threads wl, w2, 103, etc. For purpose of explanation, it is assumed the weaving begins at the upper left of Figs. 1 and la. To avoid lengthy description, the relationsbetweenthe warp elements and picks of conductor are tabulated below in Table #1. It is assumed for simplicity the number of threads in both warps are even, i. e. n of Table #1 is an even number. The letters 0 and u are used as abbreviation for over" and "under respectively. With' this preliminary discussion, Table #1 is self-explanatory of the manner in which the shuttle lays the conductor in the warps.

Table #1 Warp threads Move- 1t=oven number tion Pick ment of Layer shuttle pi To right 0 u o u o u o u Upper. 112 To leit 0 u 0 u 0 u o 0 Do. A p3 To right 0 u o u o u o u Lower. p4 To left u o u o u o 0 D0.

p5 To right o u o u o u 0 Upper. p6 Toleit u o u o .u 0 u u Do. B p7 Toright u 0 u 0 u o u 0 Lower. p8 To left u 0 u o u o u u Do.

It is to be understood the positions of the elements of each warp are transposed at the conclusion of the weaving of one section and before weaving of the next section is begun and that the weaving pattern of the subsequent sections corresponds alternately to section A and section B; for example, section C is woven in the same manner as section A and section D is woven exactly the same as section B.

As appears from Figs. 1, 1a and Table #1, the

picks of each pair pl. 92; p3. p P5. 1 9 .128.

lie side by side through the upper and lower warps, except at the edges of webbing, forming bifllar loops in a vertical section of the webbing. Each section is therefore free of any inductive loops about the warp elements except at the edges of the webbing; however, the inductive efiects of the end loops of adjacent sections mutually cancel; for example, in section A (Fig. 1) the conductor passes around the end warp element W8 of the upper warp in counterclockwise direction, whereas, in section B the conductor passes around the same warp element in clockwise direction; in section A, the conductor passes around the end warp element w8 in counterclockwise direction, whereas, in section B the conductor passes around warp element w8 in the reverse, or clockwise direction. The manner in which the inductive effects at the left edge of the webbing are caused mutually to cancel is apparent from Figs. lb -1e which show four successive loops of conductor at that edge of the web at the transition points between picks p8 and ml, 119 and pill, pill and pH, etc. The inductive effect of the loop of Fig. it) about the warp elements WI, wl, is cancelled by the inductive effect of the loop of Fig. 1c about warp element WI and the inductive efiect of the loop of Fig. 1e about warp element wl. The inductive eifeot of the loop of Fig. 1d about warp elements W2, w! is cancelled by the efiect oi the loop of Fig. 1b upon those same elements. Otherwise stated, the summation of the inductive effects of these loops upon each of the warp elements Wi, W2, wl, w2 is zero.

The two layers or plies of the woven resistor are held together by the'binder warp comprising the warp elements Bl, B2, 33, etc. As appears from Figs. 1 and 1a, the positions of the oddnumbered and even-numbered binder threads are transposed after weaving of each section A, B, C, etc. specifically, as shown in Fig. 1, the oddnumbered binder warp elements Bl, B3, B5, etc. are, in section A, under the bottom layer of the web, and pass in section B, over the top layer of the web; the even-numbered binder threads B2, B4, B6, etc. pass over the top layer of section A and beneath the bottom layer of section B of the web.

The inductance of the web resistor is negligible for reasons discussed above; the capacity effect of the resistor is negligible because there is, in use, only a small difierence of potential between any of the immediately adjacent picks of conductor.

The physical size of the completed resistor will, of course, depend upon the desired magnitude of its resistance, the cross-sectional area of the resistance conductor, and the resistivity of the conductor material. To facilitate weaving, the conductor should be flexible but strong; for example, Manganin or Nichrome wire of from .004 to .001 diameter is suitable. The conductor need not be round wire; it may be ribbonlike wire, for example, up to about .004" thick and up to about .020" wide. I

For high precision resistors having low temperature co-efllcient of resistance, the conductor may be manganin, constantan, or the like; to procure compact resistors oi high magnitude of resistance, for example upwards of 100,000 ohms, Nichrome wire may be used. As exemplary of the compactness of the woven resistors of my invention, a 300,000 ohm resistor webbing woven with Nichrome wire of .001 diameter is about 1.1 inches long and 2.35 inches wide; moreover, the web may be folded or rolled lengthwise, further to reduce its space requirements, without appreciably increasing the capacity or inductance.

Preferably, enamel-coated conductor is used because enamel insulation is thinner than silk or cotton and therefore permits the picks of conductor to be packed more closely together in the warp; moreover, a resistor of enamel-coated wire is less subject to variation from its nominal value with time and humidity than resistors using the usual silk or cotton insulation.

I When the number of elements in each of the Table #2 Warp threads I Moven=odd number Section Pick ment oi layer shuttle pl To right 0 u o u o u 0 Upper. A 92 To left 0 u o u o u u Do.

113 To right 0 u o u o u 0 Lower. 124 To left u o u o u u Do.

p5 To right o u o u o u Upgr. 3 p6 'lo left u o u o u o o 0.

p7 To right u o u o u o u Lower. p8 To left 11 o u o o o 0 Do.

It is not essential that both the upper and lower warps have the same number of threads, or that the number of threads in both warps be even or odd.

The modification shown in Figs. 2 and 2a utilizes a weaving pattern resulting in a two-layer web in which each section of the resistor consists of a single bifllar loop which is folded.

For brevity ofexplanation, the relations between the warp elements and picks of conductor are tabulated in Table #3 below; the table is based upon the assumption the weaving is begun at the upper left of the Figures 2 and 2a.

Table #3 Werpthresds Pick 3 :3 even number La er en shuttle y 1 2 a 4 5 e n-l 1;

pi Toright n o u o u o u 0 Upper. p2 Toleit o u o u o u o n Lower. E 113 Toriglit u u o u o u o u Do.

p4 Toleit u o u o u o u 0 Upper.

p5 Toriglit o u o u o u o Do. 126 Toleit u o u o u o u Lower. I p7 Toright o o u o u o u Do.

p8 Toleit o u o u o u o Upper.

' at the conclusion of the weaving of one section and before weaving of the next section is begun. Warp element W8, which may be considered as an end element of either warp, is looped by the conductor of alternate sections only.

From Fig. 2a. it clearly appears that each section of the woven resistor consists of a folded bifilar loop, one part, or fold, appearing in the upper layer of the web and another part, or fold,

appearing in the lower ply oi the web. The

completed resistor is non-inductive because (a) the current flows in opposite directions in each pair of picks in the upper and in the lower warps; (b) the current in adjacent loops of conductor about lower warp element wl flows in opposite directions, and (c) the current in adjacent loops of conductor about upper warp element WI flows in opposite directions.

The plies or layers of the resistance webbing are held together by the binder warp comprising threads Bi, B2, B3, etc. As shown in Fig. 2,

the odd-numbered binder threads Bl, B3, etc..

pass under the bottom ply of sections E, G,- etc. and over the top layer of the intermediate sections F, H, etc.; the even-numbered binder elenients B2, ER, BB, etc. pass over the top layer of the sections E, G, etc. and under the bottom layer of sections F, H, etc.

This weaving pattern-also aflords a resistor having inappreciable inductance and capacity effects even at high radio frequencies. The resulting woven resistor is compact and may be folded or rolled lengthwise without appreciabl increasingits inductance or capacity.

In Figs. 3 and 3a, there is illustrated another pattern for weaving a multi-ply resistance webbing in which the conductor forms a folded biiilar loop in each section.

Figures 3 and 3a and that there is an even number of threads in each of the warps.

Table #4 Warp threads M Moven-even number on Pick mentor Layer shuttle 1 2 3 4 5 6 n-l n pi Toright 0 u o u o u o u Upper. p2 Tolei't o u o u o u 0 u Lower. I p3 Torieht u u o u o u o u Do.

p4 Toleit o u 0/ u o u 0 u Upper p5 Toright u o u o u o u 0 Do. p6 Toleft u o u o u o u 0 Lower 1 p7 Toright o o u o u o u 0 Do.

p8 Toleit u o u o u o u 0 Upper Each section of the resistor is a bifilar loop and therefore non-inductive; considering the successive sections, conductor RC passes about the end warp element wl alternately in opposite directions and therefore the net magnetic field about that element is zero. Similarly, the magnetic field along the end warp element WI is zero because, as appears from Fig. 3, the conductor RC passes about warp element WI alternately in opposite directions. fects are inappreciable because there is insubstantial difference of potential between adjacent picks of conductor in the resistor. The resistor webbing may be folded or rolled lengthwise without appreciably increasing the inductance or capacity effects.

When the number of threads in the warps is an odd number, instead of an even number, assumed in Table #4, a slight variation of the weaving pattern results as indicated by Table #5 infra.

Table #5 Warp threads Moven=odd number Section Pick ment of Layer shuttle ,pl To right 0 u o u o u 0 Upper. p2 To left 0 u o u o u 0 Lower. I p3 To right u u o u o u 0 Do.

114 To left 0 u o u 0 u 0 Upper.

125 To right u o u o u o u Do. .l p6 To left u o u o u o 11 Lower.

p7 To right 0 o u 0 u o 11 Do. p8 To left u o u o u L o u Upper.

It is not feasible to weave resistors of low and exact'magnitude by the foregoing methods, since it would be necessary either to use wire of cross- This method involves weaving with two shutties, one of which in weaving of a section forms a biillar loop of a conductor RC in the upper layer of the webbing, and the other of which forms a bifllar loop of a second conductor ROI in the,

lower layer. The picks of conductor RC are identified by the lower case letters and the picks of conductor RCI are identified by upper case letters. In Figs. 4a., 4b and 4c, and in Table #6 infra, the weaving of COl'idllQtOI' RC is assumed The capacity efsection unsuitably large for weaving or to adjust to begin at the upper right of section M and the weaving of conductor RCI at the lower left of the same section.

Table #6 Warp threads so? m k Moyc-t n-even number L men 0 aycr shuttle l 2 3 4 5 6 n-l n pl Toleft u o u o u o u 0 Up r. M 2 'loright o o u o u o u o 1 rig u o u o u o u 0 Lower. P2 To left u o u o u 0 u u D0.

p3 To left 0 u o u o u o u Up r. N 4 To right u u o u o u o u 3 To right 0 u o u o u o u Lower. P4 To left 0 u o u o u o 0 Do.

etc.

At the left edge of. the web, the ends of the bifllar loops in the upper warp each substantially encircle the end warp element WI, but since they encircle the element alternately in opposite directions the net inductive effect is substantially zero. Similarly, the adjacent loops of conductor RC about the warp element W8 (Fig. 4a) are in bucking inductive relation. Except at the edges of the web, the pairs of picks pl, p2; p3, p4, etc.

lie side by side through the warp and form no inductive loops about the warp elements.

In the lower warp, the inductive loops of conductor RCI about the warp element wl are alternately in opposite directions so that their net inductive effect is inappreciable; similarly, the inductive loops about the warp element m0, at the right edge of the web, are alternately in opposite directions to effect mutual cancellation of their inductive effects. Except at the edges of the web, the picks of conductor RCI in each section of the resistor lie side by side through the lower warp, forming no inductive loops about the warp elements.

To complete the resistor, the two upper terminals of conductors RC and ROI are connected together and the two lower terminals of the different conductors are connected together, the current passing through the conductors in parallel and in the same direction lengthwise of the web. There is, therefore, no appreciable differenceof potential between adjacent bifilar loops of the same conductor in either layer or between,

adjacent bifilar loops of the different conductors in different layers.

As in the other modifications, the plies or layers are held together by a binder warp including elements Bl, B2, B3, etc., whose positions may be transposed between weaving of the successive sections of the resistance webbing.

Within reason, the cross-sections of. the two conductors may differ materially, facilitating obtainment of a desired magnitude of resistance for a desired length and width of the web.

Using manganin wire within the range of from #38 AWG to #44 AWG, woven resistors of this type, having values from about 25 to about 800 ohms, are about 0.55 inch long and from 0.3 to 0.8 inch wide; for the same range of. wire size,

woven resistors of this time. from about 120 to about 1500 ohms, are about 1.1 inches long and 0.8 inch wide.

The inductive and capacitative reactances of these resistors are inappreciable even at high radio-frequencies, for example, of the order of 4 megacycles per second.

When the number of elements in each of the warps is an odd number rather than an even number as in Table #6, a slight variation of the pattern results as apparent from Table #7 infra.

Table #7 War threads Moven=o dnumber Section Pick ment of hyer shuttle 1 2 3 4 6 1l-l n pl To left 0 u o u o u o Upper. M 2 Toright u u o u o u 0 Do. 1 Toright o u o u o u 0 Lower. P2 To left 0 u o u o u u Do.

p3 To left u o u o u o u Upper. N p4 To right 0 o u o u o u Do. P3 To right u o u -o u o u Lower. P4 To left u o u o u o 0 Do.

It is not essential the number of elements in each warp be the same; neither is it essential the shuttles start from opposite sides of the web, for as shown inFig. 5, the weaving of both layers of each section may begin at the same side of the web; in section Q, for example, the picks pl, p2 of conductor RC form a bifllar loop extending from the left edge of the upper layer of the web and. pick Pl, P2 of conductor RCI form a bifllar loop extending from the same edge of the lower layer of the web; similarly, in section R, the bifilar loops in the upper and lower layers extend from the left edge of the webbing.

The invention is not limited to two-ply webs; if desired, the resistance conductor may be woven on a materially greater number of warps. By way of example, Fig. 6 shows one section and part of a second of a five-ply resistanceweb having a weaving pattern generally similar to Figs. 1 and 1a. For purpose of Table #8 below, it is assumed all warps have the same number of elements and that the number of elements in each warp is an even number.

Table #8 Warp threads 8% Pi k Mozen-evon number L 0 men 0 a or shuttle y l 2 3 4 6 0 n-1 n pl To right 0 u o u o u o u 0 p2 To left 0 u o u o u o o a p3 To right 0 u o u o u o u b 114 To left 0 u o u o u o o b 8 p5 To right 0 u o u o u o u c p6 To left 0 u o u o u o o 0 p7 To right 0 u o u o u 0 u -d p8 To left o u o u o u o o p9 To right 0 u o u o' u o u c p10 To left 0 u o u o u o o 0 911 To right u o u o u o u o a 1112 To left u o u o u o u u a '1 p13 To right u o u o u o u o b 914 To left u o u o u o u u b p15 To right u o u o u o u o c To convert Table #8 to one suited for an odd number of warp threads in each layer, it is only necessary to omit the column under 1" and renumber columns 2 to 6 as 1 to 5. In Fig. 6 the shuttle begins weaving at the top layer of each section; it is feasible, however, to weave alternate sections from" top to bottom and the intervening sections from bottom to top. As in the other modifications, the plies are held together by a binder warp comprising threads Bl, B2, B8, etc.

Another example of a multi-ply resistance web having more than two plies is shown in Fig. 7. The weaving pattern is generally similar to that shown in Figs. 3 and 3a in that each section is a folded bifilar loop, the number of folds corresponding to the number of layers of plies of the webbing. Assuming the webbing has five layers and that there is-an even number of warp threads in each layer, the method of weaving is clear from Table #9 below:

Table #9 Warp threads 5 Moven-even number on Pick ment of a Layer shuttle 1 2 3 4 5 8 n-l n pl To right u o u o u o u 11 p2 To left 0 u o u o u o u 0 123 To right 0 u o u o u o u 0 p4 Toleft. o u o u o u o u d U p To right 0 u o u o u 0 u e p6 Tolcft o u o u o u o o 0 p7 Toright o u o u o u o u d 118 'Ioleft o u o u o u o u c 120 To right 0 u o u o u o u 1) p10 To left 0 u o u o u o u a p11 Toright .u o u o u o u o a p12 To left u o u o u o u o b p13 Toright 11 o u o u 0 u o 6 p14 Tolelt u o, u o u o u o d 1215 To right 11 o u o u o u o e V p16 To left u o u o u o u u a p17 Torlglit u o u o u o u o d pl8 Toleft u o u o u o u o c 1119 To right u o u o u o u o b 1220 Toleft u o u o u o u o 11 Again, it is to be noted, the net inductive effeet along each of the warp elements is zero. The subsequent sections are alternately similar to sections U and V. It is not necessary that the number of warp elements be even in each warp, or the same for different warps.

From the modifications specifically illustrated and described, it should be apparent to those skilled in the art how to utilize the invention to provide a resistance webbing having smaller or greater number of plies and which has inappreciable inductance and capacitance.

The woven resistors of any of the modifications herein described may be mounted in any suitable manner, for example, as shown in Figs. 4 to 9 of my Patent No. 1,972,499.

As exemplary of the advantage obtained by use of the hereinbefore described resistors, tests made at 4 megacycles on a three-dial attenuator with steps of 0.1, 1.0 and 10 decibels for'settings between 0 and decibels disclosed a maximum phase shift of less than 2. This attenuator had at 1000 kilocycles 1 megacycle per second) substantially the same phase angle (less than 0.5 degree) as an earlier model had at 50 kilocycles;

the earlier model used woven resistors of the type disclosed in my aforesaid Patent No. 1,972,- 499 and the impedances of the series and shunt resistors of its pads were selected to give minimum phase shift.

at high frequencies. with inferior resistors, these considerations are not important because of large errors due to the resistors themselves.

When the woven resistors herein described are used in other types of measuring apparatus, as bridges, voltage dividers, or the like, or in amplifying systems, as coupling resistors for example, due consideration should be given to the layout, wiring, and selection of the associated elements of the apparatus or system if the full benefit of this type resistor is to be realized.

Woven resistors of the multi-plytype woven with two or more conductors may be used to advantage in systems for measuring the voltageratio of potential transformers. Referring to Fig. 8, the high-voltage winding HV of potential transformer PT is connected to a source of high-voltage alternating current. One terminal of the low-voltage winding LV is connected to one terminal of the high-voltage winding and the other terminal of winding LV is connected through a suitable indicating instrument GM, for example a vibration galvanometer, to the contact PC adjustable along calibrated resistance PR in series with resistance VDR across the high-voltage winding. The resistances VDR and PR provide a voltage-dividing resistance so that the voltage-ratio of the transformer can be determined by adjusting contact PC until there is minimum response of galvanometer GM or equivalent. Resistance PR may be provided with a suitable scale cooperating with contact PC to afford direct indication of the voltage-ratio.

To measure the phase-angle of the potentialtransformer PT, the calibrated mutual inductance ML and contact PC are varied to obtain zero deflection or response of galvanometer GM. From the readings of the calibrated resistance PR and of the mutual inductance, the phase shift of the transformer may be computed.

In measuring circuits of this type, the inductive reactance of the primary MP of the mutual inductance is low compared to the total resistance tance ML is not in phase with the voltage applied to winding HV of the transformer. These effects can be rendered negligible by use of a shielded resistor formed by weaving resistance VDR on one warp of a multi-ply web and concurrently weaving a second resistance SR. on an a other warp of the web, Fig. 4 for example. The conductor used for weaving the shielding resistance SR while preferably of the same length as resistance VDR need not be of the same nominal resistance nor of material having low temperature coefficient of resistance. At one end of the webbing, the resistance conductors are connected together; the terminal of resistance VDR .at the other end of the web is connected through primary MP of the mutual inductance to the resistance PR and the terminal of resistance SR is connected to resistance FR. equal in magnitude to the resistance of PR and MP. Preferably, the webbing is rolled lengthwise about a suitable core or form of insulating material, such I as Isolantite, haying low dielectric. losses to form, in effect, two concentric tubes, the inner one comprising the voltage-dividing resistance VDR and the outer one comprising the shielding resistance SR. Since each increment of length of resistance VDR is at the same potential as an immediately adjacent increment of length of resistance SR there is no flow of displacement or charging current from resistor VDR.

It is not necessary that resistance VDR, SR be so woven in the web that each of them has negligible phase angle; for example, referring to Fig. 9, the conductor woven to form resistor VDR is disposed in the warp in the same manner as one of the conductors of Fig. 4 but the conductor woven in the upper warp to form the shielding resistance. SR follows the simple weaving pattern common in weaving of textiles. From Fig. 9, which illustrates two successive cross-sections W, X, of a multi-ply web of this type, the weaving pattern for the two conductors is self-evident.

A double shield for the voltage-dividing resistance VDR may be provided, Fig. 10, by weaving a three-ply web with three conductors. The resistance conductor woven on the inside or intermediate warp is used as the voltage-dividing resistance VDR and the resistance conductors woven on the warps on the opposite sides of the intermediate warp are used as the shielding resistances SR, SRR. All three resistances are preferably woven of conductors of equal length; it is only necessary accurately to calibrate resistance VDR, the other two need not be of the same nominal resistance nor of material having low temperature coemcient of resistance. At one end of the webbing all three conductors are connected to one side of the supply line and the other terminals of the conductor are connected to the other side of the line through the resistances FR, PR and FRRsi 'I'histype of webbing may be used flat'or rolled lengthwise if desired.

All three of the conductors may be woven so that each, as shown in Fig. 4, forms a bifllar loop in each section of the webbing but this is not necessary. As shown in Fig. 11, the conductor VDR in the middle layer is woven similarly to conductor RC, for example, of Fig. 4-; the conductors SR and SSR are woven on the top and bottom warps in the simple manner usual in tentiles. From Fig. 11, showing two successive sections Y, Z of a web of this type, the mode of weaving is evident.

As appears from Figs. 12 and 13, the voltage dividing resistance VDR may be woven in an outer layer of a three-ply warp and the shielding resistances SR, SRR woven in the other two layers. As shown in Fig. 13, only the .conductor forming resistance VDR need be woven to form a bifilar loop in each of the sections of the webbing. Frorn Fig. 13, showing two successive sections YA, ZA of the webbing, the pattern of weaving is readily understood. Preferably, the webbing is so folded the resistance VDR is substantially enclosed within the two overlying shields afforded bythe resistors SR and SSR woven in other plys of .the same webbing. Shielded resistors of the type shown in any of Figs. 8 to 13 may also be used to advantage as series resistors for the potential coil of high-voltage wattmeters and in general for applications in which it is desired to derive a current which is in phase with an applied voltage.

While I have specifically illustrated and described pr fer ed meth ds and arrangemen it is to be understood my invention is not limited thereto but is co-extensive in scope with the appended claims.

What I claim is:

1. A woven resistor having inappreciable reactance and comprising a plurality of warps, resistance wire woven thereon to forma multi-layer web, and a binder warp holding the adjacent picks of resistance wire in the different layers in relatively fixed positions.

2. A woven resistor comprising a plurality of warps and resistance wire woven thereon to form a multi-layer web, the woven wire appearing in a cross-section of the web as bifliar loops in different layers of the web.

3. A woven resistor comprising a plurality of warps and resistance wire woven thereon to form a multi-layer web, the woven wire appearing in a cross-section of the web as a plurality of serially-connected bifilar loops in different layers of the web.

4. A woven resistor comprising a plurality of warps and resistance wire woven thereon to form a multi-layer web, the woven wire appearing in a cross-section of the web as a plurality of seriallyconnected bifilar loops, one for each layer of the web.

5. A woven resistor comprising a plurality of warps and resistance wire woven thereon to form a multi-layer web, the woven wire appearing in a cross-section of the web as a folded, bifilar loop, the number of folds corresponding to the number of layers of the web.

6. A woven resistor comprising a plurality of warps and resistance wire woven thereon to form a multi-layer web, the woven wire appearing in a cross-section of the web as bifllar loops and in different layers of the web.

'7. A woven resistor comprising a plurality of warps and resistance wire woven thereon to form a multi-layer web, the woven wire appearing in a cross-section of the web as bifllar loops similarly extending from the same edge of the web and in different layers thereof.

8. A woven resistor comprising a plurality of warps and resistance wire woven thereon to form a multi-layer web, the two picks of wire in a cross-section of each layer lying side by side through the warp except at an edge of the web.

9. A woven resistor comprising a plurality of warps and resistance wire woven in sections on said warps to form a multi-layer web, each section appearing as bifllar loops in different layers of the web, the alternate sections being similarly woven on said warps, and each section differing from the adjacent sections in that thepodtions of the warp elements with respect to the picks of the conductor are transposed.

10. A woven resistor comprising a plurality of warps and resistance wire woven in sections on said warps to form a multi-layer web, the woven wire appearing in each section as a folded bifllar loop, the number of folds corresponding to the number of layers of the web, the alternate sections being similarly woven on said warps, and each section diflering from the adjacent sections in that the positions of the warp elements with respect to the picks of conductor are transposed.

11. The method of making a resistor having inappreciable time constant which comprises weaving resistance wire on superposed warps to form a multi-ply web.

12. The method of making a resistor having inappreciable time constant which comprises weaving resistance wire on superposed warps so that adjacent picks lie side by side through each of the warps.

13. The method of making a resistor having inappreciable time constant which comprises weaving resistance wire on superposed warps by passing the wire through one warp, then around an end warp element, then through the first warp in reverse direction, then through the second warp, around the end element of the second warp, and then through the second warp in reverse direction.

14. The method of making aresistor having inappreciable time constant which comprises weaving resistance conductor on superposed warps by passing the conductor in one direction through one warp, then through the other warp in reverse direction, looping the conductor about an end. element of the second warp, and then passing the conductor in the first direction through the second warp and through the first warp in the reverse direction.

15. The method of making aresistor havin inappreciable time constant which comprises weaving resistance wire on superposed warps by passing the wire back and forth through each of the warps in succession to form a resistor section, tra'nsposing the positions of the elements in the warps, and then passing the conductor back and forththrough each of the warps in succession to form the next resistor section.

16. The method of making a resistor having inappreciable time constant which comprises weaving resistance wire on superposed warps by passing the wire through the warps in succession,

and then passing the wire through the warps in reverse sequence.

1'7. The method of making a resistor having.

inappreciable time constant which comprises weaving resistance wire on superposed warps to form a multi-layer web by passing picks of wire from sides of the web and in different layers thereof.

18. The method of providing'an incrementally equi-potential shield for a measuring circuit resistance which comprises weaving resistance wires on warps to iorm a multi-ply web, utilizing one of said wires as the measuring circuit resistance, and so connecting the other of said wires that throughout the web each increment of its length is at substantially the same potential as the ad- 'jacent increment of length of the measuring circuit resistance. 

